Bug: Semi-transparent plane edges when scaling

CleverTagline Posts: 3,342 Ambassador

This appears to be a rather unique bug that only occurs in select situations, but it's definitely repeatable.

In a comp, make a new plane (any color) that's 1920x100.  In its Transform properties, unlock the scale link, and scale the plane only on its X axis.  At around 19% scale, the top of the plane will begin to become transparent.  At around 2%, this transparency will spread to about the top two-thirds of the plane.  It won't be fully transparent at the topmost edge, but it definitely won't be fully opaque as it should be.

While messing with other layers, or sometimes just switching to another program and back, this semi-transparent behavior appears to go away.  However, I tested various single-frame exports, and the export maintains the transparency despite how it may look in the view.

Scaling a full 1920x1080 plane in the same way doesn't trigger this behavior, though for what I'm doing (creating a lower-third element) I need the plane's height to be fixed from the beginning to match other elements in my comp.  I've managed to work around this temporarily by using a 100x100 plane, but this edge transparency behavior still shouldn't be happening when any plane is scaled.

This is happening in the latest release of HitFilm Express 2017 on my Mac.  System specs:

Mac Mini (Late 2014)
Mac OS X 10.10.5
2.6 GHz Intel Core i5
8 GB 1600 MHz DDR3
Intel Iris 1536 MB


  • Film_Empire
    Film_Empire Posts: 182 Just Starting Out*

    @jsbarrett So when you are stretching a plane of 1920x100px, the edges start to blur just like what would happen if you stretch a picture? If so, strange, as that shouldn't happen...

  • CleverTagline
    CleverTagline Posts: 3,342 Ambassador

    @Film_Empire - Not exactly.  When scaling a picture, I might expect the edges to soften when scaling larger, but not when scaling smaller.  And because I'm only scaling on the X axis, I wouldn't expect the top -- and ONLY the top -- of the plane to start becoming transparent at such small scale values, but that's what's happening.  The bottom and sides don't exhibit this behavior.

  • NormanPCN
    NormanPCN Posts: 4,377 Expert
    edited June 2017

    I think I remember reading some other reports about scaling and transparency on the edges so I tried to reproduce this. I can reproduce this on my Windows PC with Nvidia GPU. Different hardware.

    Also, If I scale a 1920x1080 on the X axis only, I get transparency on the top and bottom. Left/Right edges look fine. If I scale on the Y axis only then the transparency is on the left/right. Top/bottom seem fine. Appears to be an interpolation thingamajig on the opposing axis of the scale.

  • Film_Empire
    Film_Empire Posts: 182 Just Starting Out*

    Hmmm. Strange... Maybe create a support ticket...

  • Triem23
    Triem23 Posts: 20,298 Power User

    @FilmEmpire well, it's not a support ticket issue, it's an Anti-Aliasing glitch. Maybe a bug in the render code. 

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